Are pulsars gravity-wave generators?

Scientists at the European Space Agency (ESA) say that a newly discovered star could provide a test for the existence of gravitational waves.

The object, a pulsar, was discovered by the INTEGRAL spacecraft, and is one of the fastest spinning stars ever seen, rotating nearly 600 times every second. Most millisecond pulsars hover around the 300 revolutions per second mark, and the fastest spinning pulsar ever detected clocked in at 641 rps.

But even this is far short of the theoretical maximum of around 3,000 revolutions per second. Any faster that this and the object would tear itself apart. "Nature is applying some kind of brake, but we don't know what that is," MIT's Deepto Chakrabarty told New Scientist

Theoretically, a spinning body's speed should be limited by gravitational waves, the researchers say, which would carry energy away in the form of ripples in spacetime. Rapidly rotating, uneven objects are predicted to generate these waves, with faster spinning bodies creating more waves than slower ones.

The pulsar was discovered by a research team at the University of Southampton, and the findings are published in Astronomy & Astrophysics. As more super-fast millisecond pulsars are discovered, researchers will be able to tell if gravitational waves really are at work.

Chakrabarty explains that if there is a bunching of pulsars at and around the 600rps mark, this would suggest that gravitational waves are indeed involved. But if the upper speed limit tails off more gradually, then other factors are more likely responsible.

But researchers will have to wait for the upgrades to the Laser Interferometer Gravitational Wave Observatory (LIGO), to be complete before they can say for sure. These will be finished in 2008, and will be sensitive enough to detect any gravitational waves emanating from a pulsar.